This invention relates to a method for increasing the germination and growth of useful agricultural crop seeds, and to the prevention or retardation of the germination of weed seeds in admixture with the useful agricultural crop seeds. In particular, this invention is directed to the treatment of agronomic seeds particularly cotton seeds and to mixtures of cotton seeds with cocklebur seeds, whereby such seeds are provided with a coating of a C.sub.3 saturated or ethylinically unsaturated halogenated hydrocarbons, especially mixtures of chlorinated propanes and propenes. The invention also relates to coating seeds with known agronomic adjuvants in conjunction with the aforementioned halogenated hydrocarbons. Particularly preferred adjuvants are mixtures of phosphate esters such as 0,0-diethyl-S-2(ethylthio)ethyl phosphorodithioate and carbamylalkenyl phosphorous containing esters such as the dimethyl phosphate of 3-hydroxy-N-methyl-cis-crotonamide.
In the past seeds have been treated with various materials to protect the seeds prior to germination; such treatments generally have had adverse effects on the subsequent germination of the seeds.
U.S. Pat. Nos. 3,617,247 and 3,728,099 disclose the use of carbamylalkenyl phosphorous esters, alone or in combination with various materials including 0,0-diethyl-S-2(ethylthio)ethyl phosphorodithioate.
The use of 1-chloro-1,2-dibromoethane to accelerate germination and growth of plants is described in U.S. Pat. No. 3,195,997. That same patent teaches that C.sub.3 halogenated hydrocarbons have an adverse effect on plant growth when contacted with seeds.
Halogenated hydrocarbons such as Nemagon and Fumizone have been shown to be fungicidal by Dr. J. A. Pinckard who combined a dust formulation and applied it to cottonseed as a seed hopper box fungicide. (Proceedings of the Cotton Disease Council 1961-1962). Three pounds per acre of a 50% Nemagon dust containing Terraclor and 4.6% dieldrin increased stands of cotton seedlings 46% (average of 20 tests in four states).
Reduction of nematode (Reinform sp.) infection in cotton roots was shown by Wray Birchfield and J. A. Pinckard by means of the above formulation in 1961. (Phytopathology 52:747, 1962). Other plant disease causing agents such as members of the genus Pythium have been reduced by means of soil applications of the halogenated propanes and propenes such as Namagon, Fumizone, D-D and Telone. McBeth reported control of Pythium species with Nemagon (2-3 lbs. per acre) when used as a seed treatment or as a planter box application. (Proceedings, Cotton Disease Council, 1962. Published by the National Cotton Council.)
The common cocklebur (members of the genus Xanthium) is a pest weed in cotton fields and its seed passes through the cotton gins along with cottonseed, contaminating plating seed stocks. Reducing the number of cockelbur seeds tolerated by the seed purity standards allowable by state seed laws has made it desirable to remove such seeds either by mechanical or chemical means or by interfering with the germination of these pest weeds without harm to cottonseed planting stocks. It has been shown that the use of certain chemicals such as alkyl acetates and alcoholic acetic acid would reduce or interfere with the germination of cocklebur seed, see U.S. Pat. No. 3,765,865 and Weed Science 19 346-349 (1970). This method, however, has certain drawbacks with mechanically delinted cottonseed and "zip-flame" delinted cottonseed including the cost of drying the seed after treatment with the acetic acid formulation.
Mechanical removal of cocklebur seed from mechanically delinted cottonseed is not practical. Mechanical removal of cocklebur seed from acid delinted cotton seed can be accomplished.